Compile error on const definition conflicting with import

Author: igorw

Zend/zend_compile.c

@@ -7251,6 +7251,7 @@ void zend_do_use_const(znode *ns_name, znode *new_name, int is_global TSRMLS_DC)
 void zend_do_declare_constant(znode *name, znode *value TSRMLS_DC) /* {{{ */
 {
 	zend_op *opline;
+	zval **ns_name;
 
 	if(Z_TYPE(value->u.constant) == IS_CONSTANT_ARRAY) {
 		zend_error(E_COMPILE_ERROR, "Arrays are not allowed as constants");
@@ -7271,6 +7272,19 @@ void zend_do_declare_constant(znode *name, znode *value TSRMLS_DC) /* {{{ */
 		*name = tmp;
 	}
 
+	/* Constant name must not conflict with import names */
+	if (CG(current_import_const) &&
+	    zend_hash_find(CG(current_import_const), Z_STRVAL(name->u.constant), Z_STRLEN(name->u.constant)+1, (void**)&ns_name) == SUCCESS) {
+
+		char *tmp = zend_str_tolower_dup(Z_STRVAL_PP(ns_name), Z_STRLEN_PP(ns_name));
+
+		if (Z_STRLEN_PP(ns_name) != Z_STRLEN(name->u.constant) ||
+			memcmp(tmp, Z_STRVAL(name->u.constant), Z_STRLEN(name->u.constant))) {
+			zend_error(E_COMPILE_ERROR, "Cannot declare const %s because the name is already in use", Z_STRVAL(name->u.constant));
+		}
+		efree(tmp);
+	}
+
 	opline = get_next_op(CG(active_op_array) TSRMLS_CC);
 	opline->opcode = ZEND_DECLARE_CONST;
 	SET_UNUSED(opline->result);